Ground proximity warning systems (GPWS) are known and are presently installed on a wide variety of aircraft. Such systems generally provide both aural and visual warnings of inadvertent aircraft descent during flight operations. For example, a GPWS may be configured to detect an excessive loss of altitude during a landing procedure, following a take-off, or during a go-around following a missed landing approach. The GPWS also advantageously provides aural and visual warnings of potential terrain collisions during controlled flight over relatively high altitude terrain. In general, the GPWS detects an altitude loss by computing a barometric altitude (MSL) and a descent rate based upon changes in the barometric pressure. In cases where the terrain underlying the aircraft is rising relative to the aircraft, a radio altitude is computed in order to determine an altitude above ground level (AGL).
Although present ground proximity warning systems significantly enhance the safety of flight, other potentially hazardous terrain obstructions nevertheless exist. For example, radio transmission towers, smokestacks and other similar structures abruptly project outwardly from the terrain. Obstructions of the foregoing type are generally depicted in various aeronautical publications (including, for example, the well-known terminal area chart (TAC), sectional aeronautical chart (SAC) and world aeronautical chart (WAC)) and may also be represented in a variety of commonly available navigational databases that may be accessed by the ground proximity warning system so that a symbolic representation of obstacle may be displayed on a terrain awareness display (TAD) located within the aircraft.
Although the display of ground obstacles on a TAD constitutes a significant contribution to flight safety, various potential drawbacks may nevertheless exist. For example, the symbol associated with the ground obstacle may not be readily distinguishable from a terrain depiction on the TAD, so that a flight crew may fail to properly observe the obstacle on the TAD. In a further example, the terrain depiction associated with a selected geographical location may provide too many ground obstruction symbols, so that the TAD becomes excessively cluttered, which may be confusing to the flight crew.
What is needed in the art is a system and method for managing a visual display so that ground obstructions may be effectively recognized by the flight crew.